Expansive Soils (Denver, Lakewood, Broomfield: house, landscaping, new construction)

[NE Live]

Are expansive soils in higher concentrations in certain areas of greater Denver or is it sporadic throughout the whole area? I think someone mentioned Superior, CO area as being one that is having lots of problems. Is this a problem in the Western area of Denver i.e. Lakewood & Golden?

[goozer]

I don't know much about expansive soils in the Denver area, but I do know that a proper house foundation can alleviate the problems that expansive soils bring. Thus, if the house is built right, the soil should not be a problem for you.

[Katarina Witt]

Originally Posted by goozer

I don't know much about expansive soils in the Denver area, but I do know that a proper house foundation can alleviate the problems that expansive soils bring. Thus, if the house is built right, the soil should not be a problem for you.

Broomfield and parts of Louisville also have a problem with Bentonite. I agree with the above. I have had the procedure explained to me.

[Noahma]

Originally Posted by goozer

I don't know much about expansive soils in the Denver area, but I do know that a proper house foundation can alleviate the problems that expansive soils bring. Thus, if the house is built right, the soil should not be a problem for you.

this is true, a very well engineered foundation can help.

most of the eastern side of the mountains have high clay content soils. You will find poured Conc. Caisson foundations or Steel Helicoil foundations in these areas since they do resist the change in soils well. There are some areas that are soo bad that any soils engineer will tell you to never build on that land (we have had several clients that did not listen to the soils report)

If you are looking at new construction, Make sure you get a copy of the soils report and check that the builder is definatly following these without exeption. make sure the soils report you do get is Lot specific or that it was taken in very close proximity to your lot. Things can be fine in one area, and be completly different within a few hundred feet.

[NE Live]

Thanks everyone.

I am not looking to build anything new - and the question is more out of curiosity than anything else.

I just wanted to learn about which areas may be the most notorious for these problems, so if I do end up house hunting in those areas I can be extra vigilant. Does Lakewood and out to Golden have these problems?

Ok so another dumb question - Is it possible for an inspector to check the foundation to see if it is engineered, Caisson or Steel Helicoil ? I am sure it is, although I am thinking it may be a little difficult to tell on an existing home.

Thanks again.

[suzco]

Here's a good brief discussion about expansive soils from Colorado State Extension service. It's about landscaping on expansive soil, but also includes information about construction on expansive soil.

Landscaping on Expansive Soils (http://www.ext.colostate.edu/PUBS/GARDEN/07236.html - broken link)

. . .Under Colorado law, builders must let homeowners know if expansive soils are present and provide information about them. At resale, homeowners also must disclose expansive soil conditions. . .

[NickMan7]

Originally Posted by Noahma

If you are looking at new construction, Make sure you get a copy of the soils report and check that the builder is definatly following these without exeption. make sure the soils report you do get is Lot specific or that it was taken in very close proximity to your lot. Things can be fine in one area, and be completly different within a few hundred feet.

Excellent suggestion by Noahma. Our builder did do a soil test for each individual lot (and I believe they are required to by law - don't quote me on that), but during the building boom, some of the communities we looked at took a general soil sample for the entire area and many of the spec homes were suffering severe foundation issues.

Our neighbors have slightly softer soil under their home and the builder prepared their foundation differently than ours to account for the inconsistent soil. As per normal, it seems, we have a "floating" basement floor - meaning the floor is not attached to the foundation walls to allow for movement. We have very tiny hairline cracks in some window surrounds (which is normal), but that's the extent of any settling we've seen in the 3 years we've been in our house.

[Noahma]

Originally Posted by NickMan7

Excellent suggestion by Noahma. Our builder did do a soil test for each individual lot (and I believe they are required to by law - don't quote me on that), but during the building boom, some of the communities we looked at took a general soil sample for the entire area and many of the spec homes were suffering severe foundation issues.

Our neighbors have slightly softer soil under their home and the builder prepared their foundation differently than ours to account for the inconsistent soil. As per normal, it seems, we have a "floating" basement floor - meaning the floor is not attached to the foundation walls to allow for movement. We have very tiny hairline cracks in some window surrounds (which is normal), but that's the extent of any settling we've seen in the 3 years we've been in our house.

A soils test in most countys are required for permits. Each foundation needs to be engineered per lot as well. Most slabs are allowed some movement, and ones in bad soils are called "structural slab" they have more reinforcing than a slab-on-grade.

[Rich Hernandez]

You know there is a process that is so much cheaper and easier. You treat the soil so the contractor can use a more conventional foundation. Instead of Caissons and Concrete Helicoil Piers, EcSS 3000, you add it to the soil before or after the foundation has been put in place. Its injected directly into the soil and stiffins up the Bentonite and fat Clays.